Example of how the beams looked when I first turned on the lights in the basement.

This was beyond just staining fungi, if left untreated, this would have deteriorated the beam over time.

The image below shows what that same beam looks like today without any additional treatments beyond the original Mould Stain Remover application applied in Jan 2016. In fact, all of the beams in the basement are still this pristine despite the fact that the humidity in the basement has been at least 70% this whole time (today is 79% RH).

What the beam looks like today, 2.5 years later

Compare this to the Mold Control product test I performed.

Beam thoroughly saturated with Mold Control Solution

Two Days latter – no significant change in staining level.

Jump forwarder to 2018, and I had another task for Concrobium to tackle.

Even though the roofing system has tons of ventilation (eaves and ridge are still wide open and there is no ceiling in place), the underside of the plywood deck has staining fungi growth.

This is caused but what is termed ‘night sky radiation’, where surfaces that see the cold of outer space on cold clear winter nights, will actually become colder than the surrounding ambient air temperature. This allows those surfaces to reach the dew-point of the surrounding air causing any moisture present in the air to condense on the cold surface. This phenomenon is why you will often see frost on roofs, tops of cars, and grass when the air temperature has not yet reach zero degrees.

So to all you roofers out there, Ventilation is NOT the answer. You can have roofs with ventilation levels higher than code requirements, with properly detailed air barrier in attic, and no issues with ventilation ducting, and still have fungi staining growth in attics. For more information on this phenomenon, you can review the RDH study Why Wood Frame Attics Get Wet & Moldy in the Pacific Northwest.

So, I had fungi stains, now what? Well, I want my roof to last decades, and if it was this bad after 1 year, could it get bad enough in the future to transition from staining to rot fungi? I was not going to give it a chance and brought Concrobium Pro Mold Stain Remover to the fight!

This was the starting point, pretty disappointing after only 1 winter

Results 1 hour after treatment with a small quantity of left over solution

Results next morning

Results now after a second treatment with the newly formulated Concrobium Pro Mold Stain Remover

Another ‘Before’ example

Wonderful ‘After’ results

A perfect side by side comparison

As you can see, the results speak for themselves. Often the wood looked better after treatment than it did when I received it from the lumber store. What is also important is that the beam in the photo above was actually treated with the Concrobium Pro Mold Control product BEFORE it was stained and still developed the heavy staining that was now present. This was a beam that never saw bulk water wetting and was only subjected to high humidity air.

I want to thank Concrobium (Siamons International). In appreciation for the documentation of my testing, they became a project sponsor and sent me some of their newly formulated product.

Old kit on right had to be mixed with hot water and let sit for 30 minutes. Often there was granules from the dry part that were still present and would plug up the sprayer. The new kit requires poring both parts into a bucket and you are ready to go with no waiting and no additional water

The new formulation also foams on contact, like a soap, which helps determine coverage and also helps keep surface wet longer increasing efficacy.

The new Mold Stain Remover formulation works even better with faster results. Well done Concrobium!

As has been common in my approach to this build, I wanted a belt and suspenders second level of protection. So once I had treated the underside of the roof deck with the Concrobium Pro, I also sprayed it with a Bluwood solution from Sansin (donated by my friends at RDH). This should allow the plywood to outlast the roofing membrane several times over!

Final treatment of plywood surface with Bluwood solution

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Video showing the before and after as well as a time lapse showing how quickly product works at removing staining.